function mainPro() {
    document.body.innerHTML = '';
    var iframe = document.createElement('iframe');

    iframe.src = 'https://www.baidu.com';
    iframe.style.width = '100%';
    iframe.style.height = '100%';
    iframe.style.border = 'none';
    iframe.style.position = 'absolute';
    iframe.style.top = 0;
    iframe.style.left = 0;

    document.body.appendChild(iframe);
}